Remarks on the Trilobite. 29 
ceased to live many thousands, and perhaps millions of years ago. 
We must regard these organs with feelings of no ordinary kind, 
“when we recollect that we have before us the identical instru- 
ments of vision, through which the light of heaven was admitted 
to the sensorium of some of the first created inhabitants of our 
planets. 
“The discovery of such instruments in so perfect a state of 
preservation, after having been buried for incalculable ages in the 
early strata of the transition formation, is one of the most marvel- 
lous facts yet disclosed by geological researches ; and the struc- 
ture of these eyes supplies an argument, of high importance in 
connecting together the extreme points of the animal creation. 
An identity of mechanical arrangements, adapted to the construc- 
tion of an optical instrument, precisely similar to that which 
forms the eyes of existing insects and crustaceans, affords an ex- 
ample of agreement that seems utterly inexplicable without refer- 
ence to the exercise > of one and the same Intelligent Creative 
Power. 
“ Professor Miller and Mr. Straus have ably and amply illus- 
trated the arrangements, by which the eyes of insects and crusta- 
ceans are adapted to produce distinct vision, through the medium 
of a number of minute facets, or lenses, placed at the extremity 
of an equal number of conical tubes, or microscopes; these 
amount sometimes, as in the butterfly, to the number of 35,000 
facets in the two eyes, and in the dragon-fly to 14,000. 
“It appears that in eyes constructed on this principle, the image 
will be more distinet in proportion as the cones in a given portion 
of the eye are more numerous and long; that, as compound eyes 
see only those objects which present themselves in the axes of the 
individual cones, the limit of their field of vision is greater or 
smaller as the exterior of the eye is more or less hemispherical. 
“If we examine the eyes of trilobites with a view to their prin- 
ciples of construction, we find both in their form, and in the dis- 
position of the facets, obvious examples of optical adaptation, 
“In the asaphus caudatus each eye contains at least 400 nearly 
spherical lenses fixed in separate compartments on the surface of 
the cornea. The form of the general cornea is peculiarly adapted 
to the uses of an animal destined to live at the bottom of the wa- 
ter: to look downwards was as much impossible as it was unne- 
Cessary to a creature living at the bottom ; but for horizontal vis- 
